This Part Fits the following kits / parts:

#68836 - CUP JOINT ADAPTER (GEAR DIFF)

A moulded plastic drive balde that comes included #68833 - Gear
Differential Set 39T. This drive blade is a lower cost and slightly
less durable version of #68822 - POM Cup Joint Adapter (2mm hole / Black / 2pcs)
It has a 2mm drive pin hole so can only be used with TCXX drive
shafts.